OTAGO INSTITUTE

Otago Daily Times, Issue 22064, 21 September 1933, Page 6

OTAGO INSTITUTE

ASTRONOMICAL BRANCH Two interesting addresses were given before members of the Astronomical branch of the Otago Institute at the Museum on Tuesday evening, one dealing with early astronomers and the other with the construction of a telescope. Dr R. Jack presided over a good attendance. The former subject was dealt with by Mr W. H. B. Hobbs, who said that Thales, born in 640 n.c., was the first Greek to study astronomy, and, although like his countrymen, he believed that the earth was flat, he made several great discoveries, among them being that there were four distinct seasons in the year. A friend of Thales, Anaximander, was the next Greek to make important discoveries, and by making a sundial taught the Greeks to measure the time of day. Pythagoras was the next Greek who counted in science! Although he did not know that the earth moved round the sun, he was the first to assert that the earth was not fixed, but moved in the heavens. He also discovered that the evening and morning star was the same planet, then known as Phosphorus, but afterwards called Venus. After Pythngoras.came the great teacher Anaxagoras, who discovered, without the aid of a telescope, that there were mountains, plains, and valleys on the moon, which he believed was a second earth, perhaps inhabited. _ Anaxagoras knew that the planets. Jupiter, Saturn, Venus, Mars, and Mercury, moved in the heavens, and that the stars did not. In his own observatory Eudoxus, a great astronomer after Anaxagoras, made a map of all the stars then known, and was the first Greek astronomer to explain how the planets moved round, and when they would appear again in exactly the same spots. The great philosopher Democritus about this time made the remarkable guess that the bright band known as the Milky Way was composed of stars scattered like dust. Much was done for astronomy by Aristotle, who collected and compared the discoveries of his predecessors, and who stated that the earth must be a round globe. Aristarchus was one of the Greek astronomers who taught that the earth moved round tlie sun, and that the sun, like the stars, was immovable. He also taught the cause of the four seasons. In addition it appeared that he understood that day and night were caused by the earth moving on its axis once in a day, but no one believed him, and 1700 years passed before Copernicus rediscovered that truth. The most famous of all astronomers before the Christian era was Hipparchus, who collected and examined all the discoveries made by earlier observers, besides making new discoveries himself. His chief discovery was called the precession of the equinoxes. To illustrate the second subject, a.

locally-made telescope was on view, and the construction of the instrument was explained by Mr W. Gardiner, who said that the identity of the discoverer of the telescope was a matter of doubt. Experiments were made with different types of glass centuries ago, and by drawings on the blackboard he demonstrated various kinds of lenses used. Improved lenses to-day were the result of much study and correction. In 17G1 Sir Isaac Newton brought out a type of telescope which was an attempt to overcome a troublesome fringe of colour. In 1850 a Frenchman introduced another type of telescope, which was a big step forward. The speaker explained some of the methods employed in the making of the lenses, showing how focus was obtained on an artificial star. He also showed locally-made components, as well as a complete telescope. ANNUAL MEETING.

At the conclusion of the addresses the annual meeting of the branch was held. Dr Jack occupying the chair. The annual report stated that the ydhr had proved interesting and successful, although an increased membership would be advantageous. Three new associate members were elected, while two institute members, who gave valued assistance to the work of the branch in former years, were removed by death—Messrs A. D. Bell and G. M. Thomson. The death, also this year, of. Sir Thomas Sidey, Chancellor of the Otago University, for many years, rendered fitting an acknowledgment of his practical work in connection with the time system in New Zealand. Five committee meetings had been held, and six evening general meetings. The public lecture in a central hall had proved very popular. The other informative addresses aroused interest and gave rise to useful discussions, the attendance usually being good. At the observatory some members had systematically observed various stars for the records of the New Zealand Astronomical Society. Public nights (Wednesdays and Saturdays) had been conducted by the Observatory_ Committee, an increasing number of visitors indicating a marked appreciation of the privilege. Dr Focken had again represented the branch on the council of the Otago Institute, by which body the branch’s interests had been protected. The balance sheet disclosed a credit of £sl 2s 4d. The report was adopted. Dr Jack said that members should be pleased with the results of the year. Undoubtedly interest was increasing, and it was to be hoped the membership would grow. The following office-bearers were elected: —Chairman, Dr Jack; vice-chair-men, Professor D. R. White and Mr J. W. Milnes; committee—Drs R. J. T. Bell and C. M. Focken, and Messrs W. Gardiner and W. H. B. Hobbs; secretary and lion, director of the observatory, Mr J. C. Begg; treasurer, Mr W. D. Anderson,